The invention relates in general to wrenches and specifically to that special class of wrenches which are operable either by an oscillating ratcheting movement or by a torsional rotation of a shaft. This special class of wrench shall be referred to herein as a combined ratchet and torsion wrench.
Ratchet wrenches per se are old and very well known in the art. Combined ratchet and torsion wrenches are also old. See, for example, the wrench invented by A. R. McLean as described in U.S. Pat. No. 735,134 which issued Aug. 4, 1903. Other examples of combined ratchet and torsion wrenches are the invention of C. H. Marvin of U.S. Pat. No. 2,703,030 which issued Mar. 1, 1955; of Bernard L. Hofman, U.S. Pat. No. 3,707,893 which issued Jan. 2, 1973; of Wilford Flynn, U.S. Pat. No. 3,733,936 which issued May 22, 1973; and, of John K. Hunter, U.S. Pat. No. 3,972,252 which issued Aug. 3, 1976.
Briefly, a conventional ratchet wrench converts an oscillating, back and forth movement of the wrench handle to a uni-directional rotation of the wrench head output shaft. Typically, the wrench head axis is transverse to the wrench handle. Such handle oscillation mode of operation is very fast compared to a box or open end wrench, particularly in those instances where the wrench handle movement would be limited to only a small arc. In combined ratchet and torsion wrenches, a torsion shaft is provided for also uni-directionally rotating the wrench head output shaft but by a rotation of the torsion shaft about the longitudinal axis of the handle instead of by the conventional oscillating of the handle. Torsion shaft rotation is even faster than the handle oscillation mode of operation under a light load, and makes operation possible in extremely cramped and obstructed work areas where handle movement would otherwise be impossible or limited to only a few degrees of oscillation. Also, a ratchet wrench in effect includes a slip clutch which requires a minimum load and consequently will not work at all under a very light load whereas a torsion shaft can always be rotated. Usually the torsion shaft is concentric with and inside of the handle used to oscillate the ratchet mechanism.
An object of the invention is a combined ratchet and torsion wrench which can be converted from one mode of operation to the other without removing the wrench from the fastener being tightened or loosened.
Another object of the invention is a combined ratchet and torsion wrench which is easy to assemble and maintain.
An additional object of the invention is a combined ratchet and torsion wrench which oprerates even in hard to reach out of the way places.
A further object of the invention is a combined ratchet and torsion wrench which is useable from start to finish of tightening or loosening of a fastener regardless of how easy the fastener turns.